This research examined different aspects of the expression of psychometrically designated anxiety proneness related to dimensions of "ego threat" and "novelty ambiguity." In an ego-threatening situation, subjects were presented with abstract-reasoning items whose stress-relevant properties-item difficulty-had earlier been scaled among comparable samples. In the first study, comparisons focused on objective outcomes (records of task failure) as well as appraised outcome records and appraised task effort necessary for adequate performance. In the second study, comparisons emphasized direct physiological and subjective reactions to the stressing situational properties. Results indicate that anxiety proneness is associated with variation in direct reactions to the stressing properties but not with variation in the configuration of the objective or appraised properties themselves. Implications for current concepts on the expression of anxiety proneness and for its psychometric prediction are discussed, as are certain similarities between the present findings and those from research on other sources of individual differences in stress response. Differential sensitivities of alternative indices of stress reaction to variation in anxiety proneness are considered in the light of earlier studies.